SQLDialect

Topics

Basics

• name
  The name of the dialect.
• identifierQuote
  An expression (usually an SQLRaw) giving the character(s) used to quote SQL identifiers, such as table and column names.
• literalStringQuote
  An expression (usually an SQLRaw) giving the character(s) used to quote literal string values which appear in a query, such as enumerator names.
• bindPlaceholder(at:)
  A function which returns an expression to be used as the placeholder for the positionth bound parameter in a query.
• literalBoolean(_:)
  A function which returns an SQL expression (usually an SQLRaw) representing the given literal boolean value.
• literalDefault
  An expression (usually an SQLRaw) giving the syntax used to express both “use this as the default value” in a column definition and “use the default value for this column” in a value list.

Support Flags

• supportsAutoIncrement
  true if the dialect supports auto-increment for primary key values when inserting new rows, false if not.
• supportsIfExists
  true if the dialect supports the IF EXISTS modifier for all types of DROP queries (such as SQLDropEnum, SQLDropIndex, SQLDropTable, and SQLDropTrigger) and the IF NOT EXISTS modifier for SQLCreateTable queries.
• supportsDropBehavior
  true if the dialect supports the behavior modifiers for DROPqueries,false` if not.
• supportsReturning
  true if the dialect supports RETURNING syntax for retrieving output values from DML queries (INSERT, UPDATE, DELETE).
• unionFeatures
  A set of feature flags describing the dialect’s support for various forms of UNION with SELECT queries.

Syntax Indicators

• enumSyntax
  The syntax the dialect supports for strongly-typed enumerations.
• triggerSyntax
  Various flags describing the dialect’s support for specific features of SQLCreateTrigger and SQLDropTrigger queries.
• alterTableSyntax
  A description of the syntax the dialect supports for SQLAlterTable queries.
• autoIncrementClause
  An expression inserted in a column definition when a .primaryKey(autoincrement: true) constraint is specified for the column.
• autoIncrementFunction
  An expression inserted in a column definition when a SQLColumnConstraintAlgorithm.primaryKey(autoIncrement:) or SQLTableConstraintAlgorithm.primaryKey(columns:) constraint is specified for the column.
• upsertSyntax
  The type of UPSERT syntax supported by the dialect.
• sharedSelectLockExpression
  A serialization for SQLLockingClause.share.
• exclusiveSelectLockExpression
  A serialization for SQLLockingClause.update.

Modifier Methods

• customDataType(for:)
  A function which is consulted whenever an SQLDataType will be serialized into a query. The dialect may return an expression which will replace the default serialization of the given type. Returning nil causes the default to be used.
• normalizeSQLConstraint(identifier:)
  A function which is consulted whenever a constraint name will be serialized into a query. The dialect must return an expression for an identifer which is unique to the input identifier and is a valid constraint name for the dialect.
• nestedSubpathExpression(in:for:)
  Given a column name and a path consisting of one or more elements, return an expression appropriate for accessing a value at the given JSON path.